"It's good to remember the fact that there were some folks who were willing to let this industry die. Because of folks coming together we are now in a place where we can compete with any car company in the world," he said.

GM regained its title as the world's top-selling automaker in 2011, less than three years after the bail-out that many Republicans, including Mr Romney, decried as wasteful.

It included $50 billion (£31.7bn) to GM and more than $12bn (£7.6bn) to Chrysler in taxpayer-funded bail-out and bankruptcy financing, including loans and working capital. US taxpayers still own about a third of GM's equity.

Mr Romney, a former Massachusetts governor who grew up in the car hub Detroit, has said GM and Chrysler would have recovered without the injection of government funds.